A computerized microassay for complement hemolytic activity using an automated spectrophotometer

A microassay carried out with V-bottomed microplates was developed as a simplified procedure to estimate the complement hemolytic activity. This microassay has the advantage of permitting the evaluation of the extent of lysis without the need to separate the supernatants from the unlysed erythrocytes. This is accomplished by calculating the ratio between the absorbance at 405 nm and that at 450 nm. The results, read automatically on a Dynatech MR580 spectrophotometer, are transformed into CH50 U by means of a computer program. Finally, a kinetic assessment of complement hemolytic activity, easily carried out by this simple procedure, may reveal complement abnormalities otherwise undetected by the standard hemolytic assay.